Re: some keys not seen in xev(1) when pressed in combination with both Alt_L and Alt_R

[Brett Lymn <blymn%internode.on.net@localhost>]

On Fri, Dec 27, 2013 at 02:32:33PM -0600, David Young wrote:
> 
> Wow.  I thought that n-key rollover was standard behavior since the
> 1980s!
> 

Nope, blame everyone for the race to the bottom cut every corner you can
design.  To do true n-rollover you need to isolate the keys from each
other, that requires components which implies cost.

> I thought that you could count on every keyboard to generate "key
> up" and "key down" events on every press/release of every key, with
> occasional exceptions (e.g., some implementations of "lock" keys are
> odd).  Any other events or flags (e.g., indications of the modifier keys
> held down) were just a bit of "icing".  I also thought that you could
> could dependable press/release events even if you held 10 keys at a
> time, since we have 10 fingers....
> 

No - the keys are organised in a matrix and the keyboard controller
scans the row/columns to work out the keys pressed.  They take some
short cuts to limit the number of lines used which means that some key
combinations are not available, a design tradeoff.

> Is there a "raw" mode for these keyboards that activates n-key rollover?
> 

Nope, it is a limitation on the hardware - blame everyone for wanting
the cheapest keyboard they can find :)

-- 
Brett Lymn
Staple Guns: because duct tape doesn't make that KerCHUNK sound - xkcd.com